Switch contact



Jun 12. 1928.

C. T. HANNA SWITCH CONTACT Filed Jan. 5, 1923 Inventor Charles T. Hanna, y His Attovney.

Patented June 12, 1928.

UNITED STATES PATENT OFFICE.

CHARLES THOMAS HANNA, OF RUGBY, ENGLAND, ASSIGNOR '10 GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

SWITCH CONTACT.

Application filed January 3, 1923, Serial No. 610,515, and in Great Britain February 14, 1922.

This invention relates to devices for electric circuits and more particularly to devices of the type in which contacts carried by a retatable drum engage with pivoted fingers.

In such devices it is essential to provide means tor adjusting the pivoted finger so as to vary the pressure with which it engages the contact, and. it has hitherto been customary to provide a spring for this purpose which surrounds an adjusting member such as a stud passing through the finger and secured to the stationary member on which it is pivoted. It has been diilicult to obtain a satisfactory method of locking the adjusting stud so as to prevent it from working loose it subjected to vibration or from any cause. One of the objects of the present invention is to provide an improved and efficient method of locking such adjusting studs, and to that end it consists in providing a stud adapted to be screwed into the stationary member of the contact linger and provided with a squared portion engaging with a washer which has projections on its under side which enter slots or depressions formed in the pivoted member of the finger, the spring being mounted between the washer and a nut secured to the outer end of the stud. A further object of the invention is to provide an improved form of pivot for such fingers, and to that end it consists in "forming the pivot tor the finger with a cylindrical portion capabio of rotating through a considerable angle in a socket formed in the fixed member. This socket is so shaped that while the cylindrical portion of the pivot can rotate through a considerable angle within the socket it can only be retrieved from it by movement in a longitudinal direction, which movement is normally prevented whenthe finger .is completely assembled.

he accompanying drawings illustrate this invention, Fig. 1 being a side elevation of a complete linger and Fig. 2 a view oi the adjusting stud.

In the drawings 1 represents the movable contact member which is pivoted on the stationary member or support 2 at 3 and carry 'ing a contact 4. adapted to engage the contacts on a drum. The contact tip 4: and the member 1 including the pivot 25 comprise what is known in the art as a contact finger. Member 1 is made channel-shaped in cross section and the adjusting member or stud 5 passes through its upper side and is screwed into the stationary member 2 as shown in dotted lines. The stud, is provided with a collar 6, secured to or formed integral with it, upon which the member 1 is supported. A coiled spring 7 surrounds the upper portion of the stud and a nut 8 is secured to the outer end of the stud, so that the stud and spring form a resilient connection between the contact member and the stationary support. This nut may be made rigid with the stud by screwing it down to the end of the threaded portion and splitting and opening the end of the stud. This prevents any possibility of the nut working loose and at the same time permits of the renewal of the spring it required. The lower end of the spring is supported on a washer 9 which has a square aperture through which the squared portion of the stud passes, so that the washer is interlocked with the stud to rotate therewith. The lower side of the washer is provided with two projections 10 which cooperate with slots or depressions 11 formed in the upper side of the member 1, and this washer forms a pin and slot connect-ion between the stud, the support and the contact member.

The pivot 3 for the member 1 consists of a substantially L-shaped piece of metal having a cylindrical enlargement at the extremity of one of the limbs, which fits into a socket or slot formed in the member 2. The cross section of this socket is circular for more than 180 so that the enlargement can only be inserted from the side but when inserted can rotate through a considerable angle. The side portions of the member 1 enclose the ends 01 the L-shaped piece and prevent it from becoming displaced after the contact has been assembled. In pivoted contacts as hitherto constructed the pivot was prevented -from coming out of its socket only by arranging the adjusting spring in close proximity to the pivot. Such an ar rangement was not entirely satisfactory as the pivot was not positively locked in its socket and a very strong spring was required otherwise the pressure exerted by it on the contacting portion of the finger was very small.

TVith the present construction, in order to increase the pressure of the finger 4 upon the drum contact, the nut 8 is rotated, this causes the stud to be screwed into the member 9.. It will also be observed that the fit) adj ustment, of 1 thestud does not: change, the tension o'l the spring while finger 4 is out. of contact with its cooperating contact. As the washer has to rotate with the studthe projections lO'are withdrawn from the slots and ride over the surface of member 1 until they again come into register with the. slots when the stud will again be locked in position against accidental. displacement.

The member 2 may be secured to an insulated' rod by means of bolts 12 andstrap 13 and-current is led to linger 4 from flexible conductor 14s secured to the upper bolt, through conductingstrips 15 and member 1.

What Lclaim as new and desire to secure by Letters Patent of the United States, is

1. A switch contact comprising a contact linger, a support for the same, a resilient connection between the contact finger and the' support comprising an adjusting member extending through the contact finger intermediate the endsof the finger for adjusting the position of the contact finger with respect to the support, the said connec- -t ion inc uding a spring surrounding said member and co-acting with said-finger, and an interlocking connection between the said :uljustingmeinber and the said contact finger for locking the adjusting member with the support.

As'an element of a switch contact provided with a contact member which is mounted to move pivotally about a support and which is adjusted to and yieldingly restrained in a predetermined position with respect to the support by means of an adjusting member and a spring interposed between the adjusting member and the contact member, a'w'asher mounted upon andinterlocl'ced with the adjusting member and-arrangedto interlock with thecontact member for maintaining the adjustment of the adjusting member.

3. As an element of a contact finger provided with a contact member which is mounted to more pivotally about a support and which is adjusted to and yieldingly restrainedin a predetermined position with respect to the support by means of a rotat ableadjusting member and a spring interposed between the adjusting member and' the contact member, a washer interposed be tween the contact member and'the spring, the saidwasher arranged to interlock with the adjusting member to be rotated therewith and arranged to be held in interlock? ing engagement with the contact member by. the spring so as to maintain the adjustment of the adjusting member.

4. As an element of a switch contact provided with a contact member which is mounted tomove pivotally about a support and which is adjusted to and yieldingly restrained in a predeterminedposition with respect to the support by means of a. ro-i tain the adjustment of the adjusting member.

5. A switch contact comprising a sup.. port, a contact member having atoneend a part cylindrical pivotal bearing on saidsupport which permits the contact member to. rotate through a considerable angle and-non.

mally preventsthe removal of the contact.

member, an adjusting stud mounted fOli" adjustment on said support. and extending through the contact member intermediate -its ends, a coil spring slu'rounding said studfor yieldingly holding the contact member in position with respect to the support, anda washer upon whichthe one end' of the said spring presses which interlocks with the said stud and forms a pin andslot connection between the contact member and the stud--for maintaining the adjustment oftheistud,

6. A switch contact comprising a contact member with an opening therein, a stud extending through said opening, the. opening and stud being so formed as to permitfrotar tion of the studwith respect to said contact member, said contact member being movable with respect to the stud longitudinally thereof irrespective of the rotation of the stud, means engaging the stud and the contact member to prevent rotation of the studwith respect to the contact member and disengage able from one of these elements to permit such rotation. i

7. A switch contact comprising a contact member with an opening therein, a studev tending through said opening, the opening and stud being so formed as to permit rota-3 tion of the stud with respect to said contact me i'nber, said-contact member being movablev with respect to the stud longitudinally thereof irrespective of the rotation of the stud, a washer fitted upon the stud to preventrotation and to permit longitudinal movement of the washer with respect to theistud, and cooperating means upon the washerandcontact member which are engageable. to pre-. vent rotation of saidwasher with respectto said contact i'nen'lber, and disengageable to permit such rotation. i i

8. A switch contact comprising a contact member with an opening therein, a studiex tending through said opening, said, opening and stud-cbeing soformed astdpermitirotas said washer and contact member provided 10 respectively with a projection and recess which are relensubly held in engagement by the pressure of the coiled spring upon the washer.

In witness whereof, I have hereunto set 1 my hand this ninth day of December, 1922.

CHARLES THOMAS HANNA. 

